Ruggedized host module

ABSTRACT

An energy dissipative element ( 24 ) protects hard disk drives ( 22, 72, 92 ) from shocks and vibrations. A closed elastic envelope ( 48 ) houses a body of open cell foam ( 54 ), a volume of viscous liquid ( 56 ), and a compressible gas ( 64 ). Under compression or expansion of the foam ( 54 ), viscous liquid ( 56 ) flows through cell orifices and thereby dissipates energy resulting from external force applied against the elastic wall ( 48 ). The energy dissipative elements ( 24 ) are applied between a disk drive housing ( 22 ) and an outer case ( 26 ) to create a ruggedized portable disk drive module ( 20 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. 120 as acontinuation-in-part of U.S. patent application Ser. No.10/604,388 filedJul. 16, 2003, co-pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to electro-mechanical devices. Morespecifically, the invention relates to a housing or mounting assemblywith diverse electrical components, especially to electronic systems anddevices. The invention relates to methods and apparatus for cushioningof a computer peripheral from mechanical shocks and vibrations,especially a memory unit peripheral such as a disk drive. The method andapparatus employ highly viscous fluids that flow readily at ordinaryambient temperatures, operative in a porous elastic structure.

2. Description of Related Art

Including information disclosed under 37 CFR 1.97 and 1.98—The term“disk drive” may refer to any of several types of devices, including butnot limited to hard disk drives, floppy disk drives, and optical diskdrives such as CD and DVD drives. These disk drives share a commoncharacteristic of having one or more rotating recording media disks, andhaving a transducer positioned over a surface of the media. Disk drivesalso share the characteristic of being highly susceptible to damage, inpart due to external shock and vibration and in another part due tointernally generated vibrations that are not sufficiently damped by thedisk drive mounting.

A drive using fixed rotating disks inside it is called a fixed diskdrive. A drive using removable disks enclosed in an envelope is called aremovable media disk drive and the envelope containing the disks iscalled a removable disk cartridge. When the fixed disk drive itself isenclosed in an envelope and a shock resistant system is placed betweenthem, then this assembly is called a removable drive module. A removabledisk cartridge is removable from a disk drive while a removable drivemodule is removable from a docking device installed in a computer or anarray chassis. Examples of removable disk cartridges include bothindustry standard floppy disks and removable hard disk cartridges. Manymanufacturers supply floppy disks. The 3.5-inch form factor designationdoes not necessarily refer to any dimension of a drive, itself. Rather,it refers to size of the disk that is designed to fit into the drive.Examples of removable disk cartridges include commercially availableproducts supplied by companies such as Iomega, Castlewood and SyQuest.DataZone Corporation of Felton, Calif., manufactures and sells a priorart removable drive module under the trademark, DataBook. The drivemodule can utilize an optical disk drive, a tape drive and other suchdrives besides hard, magnetic disk drives.

One application of the present invention relates to removable drivemodule technology. In known prior art, foam, polymeric material,mechanical springs or a combination of these materials and devicesprovide shock and vibration protection to a disk drive. However, thesefall short of achieving the shock protection needed for a drive tosurvive a variety of common impacts, which can produce shock at a levelreaching approximately 5,500 Gs for a 3.5 inch disk drive and 13,000 Gsfor a 2.5 inch disk drive. The present invention overcomes thislimitation.

The following patents show state-of-the-art damping schemes. Such priorart includes U.S. Pat. No. 6,351,374 to Sherry; U.S. Pat. No. 6,249,432to Gamble et al.; U.S. Pat. No. 6,1 54,360 to Kaczeus Sr. et al.; U.S.Pat. No. 5,837,934 to Valavanis et al.; U.S. Pat. Nos. 4, 638, 383 and4,568,988 to McGinlay et al., and U.S. Pat. No. 3,384,221 to Houtman.These patents provide limited teachings that refer only to foammaterials, which do not achieve the desired degree of protection.

U.S. Pat. No. 6,154,360 to Kaczeus, Sr., et al. is assigned to DataZoneCorporation. It shows a data storage subsystem that purports to becapable of withstanding several four-foot drops. A data storage devicesuch as a hard disk drive is partially surrounded by a speciallyconfigured foam enclosure, formed, for example, of polyurethane foam. Inturn, the foam enclosure and 2.5 inch disk drive are encased within ashock resistant module housing, such as one formed of high impactplastic. Within the module housing, the foam enclosure surrounds thenarrow periphery of the disk drive and supports both the top and thebottom broad surfaces of the disk drive. The module housing is slottedfor ventilation.

U.S. Pat. No. 6,249,432 to Gamble et al. discloses a removable hard diskdrive mounted in a carrier or tray for insertion into a docking bay. Athree-component vibration damping system reduces vibration between thehard disk drive and the carrier and between the carrier and the dockingbay of a computer using such drives. One component is composed ofpolymeric material and is located between the exterior of the carrierand the interior of the docking bay. A second component of similarpolymeric material is located between the interior of the carrier andthe exterior of the hard disk drive with an interference fit. The thirdcomponent employs metal or polymer springs and polymeric pads locatedbetween the exterior sides of the carrier and the interior sides of thedocking bay. This patent relates only to disk drives and not to generalpackaging and protecting of objects and systems.

U.S. Pat. No. 6,351,374 to Sherry discloses a hard disk drive modulehaving a protective cover housing or a modular case. The module usesinsulator foam or other resilient material on one side or edge of theunit so as to maintain engagement with the other side or edge of amodular case. The resilient material can reduce shock to the disk driveunit due to impact on either the case or the chassis. Even a flexiblecable leading to an electrical connector is attributed with thequalities of a shock absorber. Thus, this patent teaches a degree ofshock absorption, but the extent of shock absorption appears to be low.

U.S. Pat. No. 5,837,934 to Valavanis et al. presents the use of foamsheets to provide shock absorption. It neither anticipates nor suggestsapplications for protecting other objects, systems, or devices by use ofviscous means.

U.S. Pat. Nos. 4,638,383 and 4,568,988 to McGinlay et al. teach ananti-vibration mount using an elastic rubber material known as AVM 206for disk drives. This mount material has a capability of 40 Gs ofnon-operating shock from the elastic deformation property of thematerial. The shock absorption of this class of elastic or rubbermaterials is limited compared to what is required to addressnon-operating shocks reaching a level of 5050 Gs. This patent employs noviscous means to protect a disk drive from shock or vibration.

U.S. Pat. No. 3,384,221 to Houtman claims the invention of adding aplurality of fingers or cuts in foam padding used for shock protection.A package can be dropped from a maximum height of 76.2 cm (30 inches).Under conditions where prior art shock would be 47.8 Gs, Houtman'stransmitted shock is within 11 Gs. However, this patent neither suggestsnor discloses the use of viscous liquid to damp shock or vibration.

Additional prior art includes U.S. Pat. No. 6,347,411 to Darling; U.S.Pat. No. 6,339,532 to Boulay et al.; U.S. Pat. No. 6,039,299 to Ohnishiet al.; U.S. Pat. No. 5,995,365 to Broder et al.; U.S. Pat. No.5,965,249 to Sutton et al.; and U.S. Pat. No. 5,510,954 to Wyler. Thesepatents mention the use of viscous materials. However, they do notanticipate the methods and apparatus used in the present invention.

U.S. Pat. No. 6,347,411 to Darling discloses the use of viscous liquidsand micro-balloons but does not present an interaction between a viscousliquid and an elastic, self-forming structure. Viscous liquid is used todissipate energy within a closed cell material that entraps the liquid.The viscosity of the liquid is specified between 100,000 centistokes(cs) and 2,000,000 centistokes. These very high viscosity fluids arecharacterized as solids that exhibit cold flow or creep. Various testingmeasures the characteristics of materials that cold flow or creep at lowrates. The viscous fluids are encapsulated and entrapped within a cellto provide dissipation of shock energy at the microscopic and molecularlevel of the viscous fluid. In contrast, the present invention providesfor dissipation of energy at the macroscopic level where liquid flowsbetween cells of an internal structure and inside of an externalmembrane.

U.S. Pat. No. 6,339,532 to Boulay et al. discloses mounting a disk driveby a layer of viscoelastic material, such as double-sided foam tape,between the drive and an enclosure. Primary and secondary mountingplates may employ the viscoelastic material between them, and theseplates should have aligned ventilation holes for cooling. This mountingcontrols internally and externally developed vibration relative to adisk drive but does not extend the performance capabilities to protectit from operating or non-operating shock. The viscoelastic material,sandwiched between two plates, dampens vibrations that may otherwiseaffect recording device performance or cause tracking errors. However,Boulay does not suggest the use of a viscous liquid for damping. Rather,a viscoelastic material in the form of a foam pad damps operationalvibration but does not protect from shock. Further, the protectivemounting primarily is effective during operation, when the device ismounted into an enclosure. Thus, Boulay does not envision protection ofa device outside of the enclosure.

U.S. Pat. No. 6,039,299 to Ohnishi, et al. discloses a viscous damperfor a disk-reproducing unit. The damper consists of a viscous fluid andtwo elastic cavities connected by a tube to a protuberant cavity.Damping occurs due to shear forces at irregular formations of bothsurfaces of the cavities and involves flow through the single orifice ofthe connecting tube. This technology is applied to a disk-reproducingunit that is always found in a manufacturing area. As such, it is notsubject to the shock danger encountered by a portable device. Thispatent is readily distinguished from the present invention in that itdoes not suggest the use of an open celled material or a structureproviding a multitude of orifices.

U.S. Pat. No. 5,995,365 to Broder, et al. teaches the use of flexiblecables to reduce the transfer of shock forces among electroniccomponents such as a motherboard and a hard drive-carrier assembly. TheBroder patent also teaches a method of using articulated arms as shockabsorbers. This teaching does not suggest an encapsulated viscous liquidthat transfers to and from elastic open cells to dissipate shock andvibration. The energy dissipation is at a molecular level and not at amacroscopic level as envisioned in the present invention.

U.S. Pat. No. 5,965,249 to Sutton, et al. teaches a cold flowingmaterial with high internal cohesion forces. Fluid is entrapped betweencells of porous material. Molecular level dissipation within the fluidproduces damping. Cold flowing material produces only smalldisplacements on a microscopic scale. Thus, it is unlikely that suchmaterials can absorb shocks up 5,500 to 13,000 Gs.

U.S. Pat. No. 5,510,954 to Wyler teaches acoustic shielding. A keyelement is a fluid impervious barrier layer located next to soundabsorptive porous foam. No liquid is located within the cells of theporous foam. A pouch contains liquid, but this liquid is separated fromthe foam layers by an impervious membrane of the pouch. The acousticshielding employs no viscous liquid or porous elastic structure.

Various other patents show background art. U.S. Pat. No. 5,546,250 toDiel uses an elastomer seal to cover the frame of a drive and absorbexternal loads applied to the edges of the housing. The protectionsystem is applied to a disk drive perimeter rather than to a module.U.S. Pat. No. 4,891,734 to More et al. shows the use of an elastomerbody to encapsulate an electronic assembly that is confined in a closedcavity of a structure subject to vibration and shock. U.S. Pat. No.5,216,582 to Russell et al. describes a housing assembly that forms afixed disk drive module for a low profile fixed disk drive that isshock-mounted therein. Both More and Russell use elastomer supports toprotect from shock and vibration.

As an example of the available technology in a current commercialproduct, the Maxtor XT 5000 external hard drive uses two plasticstructures which cover four corners and two long edges of the case. TheMaxtor 5000XT manual warns not to bump, jar, or drop the drive. TheMaxtor specification for this drive is 250 G for linear shock.

Other literature references provide pertinent background. In apioneering work, Dynamics of Package Cushioning, R. D. Mindlin describesthe dynamics of package cushioning in terms of mathematicalformulations. C. W. Radcliffe applies a viscous fluid damper to problemsof prosthesis in Biomechanical Design of a Lower-Extremity Prosthesis.Specifically, a vane or a piston is used to move a viscous liquid fromone chamber to another through a carefully designed orifice to affect adesired performance characteristic for a prosthetic knee mechanism.

Various commercial devices employ viscous liquids. For example,automobile shock absorbers operate with viscous liquids. Many industriesuse similar devices, with rigid chambers to hold the viscous fluid andorifices to control its flow.

Still other literature references show the importance of shock andvibration protection in the disk drive industry. See, for example,Stevens, L. D. et al: Magnetic Recording Technology; Chen and Kumano:The Efficacy of Mechanical Damper in Actuators for Rotating MemoryDevices; Lilley, D. T.: The Discussion of Some Engineering Trade-offs inWinchester Disk Drive Isolation and Shock Protection; and The Effects ofShock & Vibration on Rigid Disk Drives, by ATASI Corporation.

The above prior art analysis contrasts the essential or often occurringelements of certain embodiments of the present innovation. The presentinvention comprises additional embodiments that may or may not includeall the elements listed above. All observations provided herein aredirected to optional aspects of the present invention and are in no wayexpressions of limitations to the full scope of the present invention.

Portable Data Storage—According to standards established by variousauthorities, a minimum requirement for portability of disk drives is theability to survive multiple drops from a height of 91.44 cm (36 inches)onto a hard surface. Prior art devices have had difficulty in meetingthis standard while conforming the product to the popular 3.5-inch formfactor. The best-known performance in the prior art is by DataZoneCorporation, which supplies a commercially available hard disk drivecartridge. This product uses a foam enclosure inside of a shockresistant housing. This product faces the shortcoming of not conformingto the popular 3.5-inch form factor. The size of the DataZone cartridgehousing is larger than that of the popular 3.5-inch form factor harddisk drive, evidently because the excessive size is required tosufficiently protect the disk drive. The DataZone module provides littleif any protection against external shock for a 3.5-inch form factor harddisk drive. The product apparently is limited to the use of 3.0 inch andsmaller hard disk drives.

Removable media can meet the minimum shock requirement for portability.Iomega, SyQuest and Castlewood are commercial producers that haveshipped hard disk drive devices using removable media. The hard disk iscontained in a portable cartridge that can be removable from the drive.An inherent problem with removable media for hard disk drives is thatthe media becomes contaminated, and this contamination transfers to thetransducer in the drive. To counter the effects of the contamination,the recording capacity of the media is relatively decreased and thereliability of the overall system is compromised.

Floppy disk, CD, and DVD are other removable media. These media are muchless susceptible to contamination. However, the capacity of therecording media is 0.01% to 1.0% of the capacity of a comparable sizehard disk drive. These low capacities limit the application andusefulness of the removable media disk drives. In addition, the largenumbers of floppy disks, CDs, and DVDs, which are often needed and used,require a large and carefully cataloged library. This same informationis better stored on a single hard disk drive that has electronic meansfor cataloging.

There is a need for a disk drive module that can withstand high,non-operational G-shock and meet vibration specifications for commercialand personal use. These specifications define levels of shock andvibration that the device must safely and reliably withstand at aminimum.

Shipments of Disk Drives—There are design standards for common carriershipments based upon size and weight of a container and whether thepackage is shipped on or off a pallet. Special shipping containers haveto be designed to protect all shipments of disk drives. A percentage ofcommon carrier shipments experience shocks in excess of the designstandards, resulting in costly damage and possible loss of data.Individual disk drives are shipped in expensive and bulky boxes linedwith foam or other bulky, shock absorbing, paper-based material.

Environmental concerns and new laws require recycling of packingmaterials. Foam and other polymeric materials are extremely difficult torecycle. Secondary shipment costs of these packaging materials are highbecause they have to be used in large volumes for adequate protection ofdelicate peripherals or instruments.

There is a need for a disk drive module that can withstand high G-shockfor shipment by common carriers, eliminating the need for the design ofspecial and expensive shipping containers.

Disk Drive Mounting—Whether the hard disk drive is mounted as a singlecomponent in a system or as an array of many disk drives, the mountingdesign is crucial to obtaining optimum performance and enhancedreliability. Previous mounting schemes use foams, polymeric materials,viscoelastic materials, mechanical springs or a combination of thesematerials and devices to provide the required shock and vibrationdamping to the disk drive.

These previous mounting schemes either mount the drive to a solid memberof a case that incorporates shock and vibration damping material ormount the drive in a cartridge or module having shock and vibrationisolation and damping. The cartridge or module is then attached to asolid member of the case, with or without damping materials.

The design requirements for these mounting schemes are becoming morecritical because: 1) Disk drive rotational speeds are increasing.Typical rotational speeds for hard disk drives have increased from 5400rpm to 7200 rpm, with some drives now rotating at 10,000 rpm and 15,000rpm. Slight imbalances will result in large vibrations and/or largeforces that will accelerate component wear and induce damage to thedrive(s).

2) Larger dense arrays of disk drives require smaller individualcontributions in vibration forces from each individual drive. The drivesare all rotating at the same speed. Thus, the probability of excitingnatural vibration frequencies between the elements of the array is high.

Building of systems incorporating hard disk drives requires carefulhandling of each and every hard disk drive. Currently, during theprocess of removal from the shipping container and installation into asystem or system module, there is no significant protection afforded tothe hard disk drive. Typically, this operation is done by semi-skilledlabor, worldwide. The largest numbers of hard disk drive failures happenduring this installation process.

There is a need for a disk drive module that can both protect the harddisk drive during system assembly and meet the vibration and shockrequirements. This is irrespective of whether the system uses a singlehard disk drive or an array of disk drives.

Commonality of Form Factor—The high volume production growth in the diskdrive industry is supported by common form factors.

Form factors for 3.5-inch, 3.0-inch, 2.5-inch, 1.8-inch, and 1.0-inchdevices are well defined and accepted worldwide. However, there is noaccepted form factor for a hard disk drive module. Besides the DataZoneruggedized module form factor, there are other, un-ruggedized modules ofdifferent dimensions being offered by many companies. These modules arenot interchangeable for numerous reasons, size being one of them.

It would be desirable to define a form factor for hard disk drivemodules or to conform to an existing form factor. This advance wouldlead to increased module manufacturing, higher volumes, and reducedcosts. Producing a maximum protection for shock and vibration within afixed form factor is a further competitive advantage. The smallest formfactor module of the present invention provides high G-shock protectionto the 3.5-inch form factor hard disk drive, which is the largest formfactor in high volume production.

To achieve the foregoing and other objectives and in accordance with thepurpose of the present invention, as embodied and broadly describedherein, the method and apparatus of this invention may comprise thefollowing.

SUMMARY OF THE INVENTION

Against the described background, it is therefore a general object ofthe invention to provide improved protection from shock and vibrationfor electronic devices, especially disk drives and other data storagedevices, which may by portable or fixed.

Another object is to create a ruggedized data storage subsystem,preferably enabling the use of common form factors such as 3.5-inch,3.0-inch, 2.5-inch, 1.8-inch, and 1.0-inch form factors.

According to the invention, an energy dissipative element is used forprotecting a hosted device from deleterious effects of mechanical shocksand vibrations. The energy dissipative element has a closed envelopeformed of an elastic, resilient wall that encloses an internal volume. Aporous body of elastic material is contained within the internal volumeof the closed envelope. The porous body defines a network of cellsinterconnected through cell orifices suitably configured for passingviscous liquid between cells. A viscous liquid is contained within theenvelope and fills at least a portion of the network of interconnectedcells. A compressible gas also occupies a portion of the internal volumeof the envelope. Under compression or expansion of the porous body, theviscous liquid flows through the cell orifices and thereby dissipatesenergy resulting from an external force applied against the elasticwall.

The closed envelope can be made of latex rubber, such as from latexrubber tubing. The opposite ends of the tube are sealed to create theclosed envelope. A suitable seal can be chosen from a bonded seal, anadhesive seal, a compression seal, and any combination of these. Abonded seal can be achieved by vulcanizing the latex rubber at the endsof a tube. An adhesive seal can be achieved by gluing shut the end of atube. Adhesives such as cyanoacrylate glue are suitable. A mechanical orcompression seal can be achieved by applying a band of shrinkablematerial to a tube end and shrinking the band, thereby compressing shutthe end of the tube.

Open cell foam is one type of porous body that defines a network of cellorifices with relatively small apertures between juxtaposed cells.Substantial portions of the cell orifices are relatively smaller intransverse dimension than the cells interconnected by them so that theviscous liquid is restrained during movement between cells. A preferredviscous liquid is polydimethylsiloxane (PDMS). Suitable viscosity isless than 20,000 centistokes (cs). A preferred viscosity range isbetween about 1,000 cs and about 50 cs, with 500 to 1000 cs being astill more preferred range.

According to another aspect of the invention, a host module assemblyprotects a hosted device from shock and vibration. The assembly includesa case or container configured to receive a hosted device therein and toreceive at least one mechanical energy dissipative element between thehosted device and the case. A hosted device and at least one mechanicalenergy dissipative element are located within the case. The mechanicalenergy dissipative element is formed of a closed envelope having anelastic, resilient wall that defines an enclosed internal volume. Aporous body of elastic material is contained within the internal volumeof the closed envelope. A compressible gas also occupies a portion ofthe internal volume of the envelope. The porous body defines a networkof cells interconnected through cell orifices suitably configured forpassing viscous liquid between cells. A viscous liquid is containedwithin the envelope, filling at least a portion of the network ofinterconnected cells. Under compression or expansion of the porous body,the viscous liquid flows through the cell orifices and therebydissipates energy resulting from an external force applied against theelastic wall.

The hosted device can be a disk drive with a traditionally shaped,box-like housing having six faces arranged in three opposite pairs offaces. The case is suitably sized to receive at least one mechanicalenergy dissipative element between each face of one or more oppositepairs and the case. Correspondingly, at least two of the mechanicalenergy dissipative elements are located between the disk drive housingand the case, with at least one between each of the opposite faces of atleast one pair of opposite faces of the disk drive housing and the case.At least one mechanical energy dissipative element can be locatedbetween each of the six faces and the case.

The hosted device can have one or more pairs of opposite sides and cancarry a pair of rails on one or more pairs of the opposite sides. Atleast one of the mechanical energy dissipative elements is locatedbetween each of the rails and the case.

The case is configured with at least one external corner edge. A bumperformed of elastomer material is attached over the corner edge. Apreferred elastomer material for the bumper is of 35 dm to 75 dm.

In a specifically desirable version of the invention, the hosted deviceis a disk drive and the case is a common form factor envelope. Theresulting structure provides a ruggedized disk drive module. The diskdrive can be selected from 3.5-inch, 3.0-inch, 2.5-inch, or 1.0-inchform factor disk drives. The case can be adapted for mounting into acomputer system, with the result that the mechanical energy dissipativeelement provides the protection from shock and vibration during theinstallation of the disk drive module into a computer system. Either asingle disk drive cartridge or a plurality can be mounted into acomputer system. The mechanical energy dissipative element is functionalto protect against shock and vibration during the installation of aplurality of the disk drive modules into a dense array of disk drives ina computer system. The case also may be a container used in handling adisk drive during manufacture or installation, protecting the disk drivefrom shock and vibration during handling.

The hosted device can be a portable electronics device. Suitableexamples are a personal digital assistant (PDA), camera, camcorder, orliquid crystal diode (LCD) panel.

Another aspect of the invention is a method of dissipating energyreleased due to external forces that cause mechanical shocks andvibrations to a disk drive. Placing a plurality of closed elasticenvelopes around the disk drive carries out the method. Open cellmaterial is provided within each of the envelopes. The open cellmaterial has orifices communicating at least some of the cells with oneanother. At least some of the cells are filled with a viscous liquidmaterial. In response to an external mechanical force applied on theelastic envelope, the envelope deforms. It forces the viscous liquidthrough the orifices from one cell to another. This dissipates energyfrom the external mechanical force.

The method may include further steps of returning the elastic envelopeessentially to its original shape due to the energy stored in theenvelope as a result of its deformation. This also returns the viscousliquid through the orifices from one cell to another by forces generatedwithin the viscous liquid.

According to another aspect of the method, a hosted device is protectedfrom shock and vibration while carried in a host module assembly. Thehosted device is isolated from direct reception of shock by attachingside rails to opposite edges of said hosted device. Elastic dampers areapplied between the side rails and the host module in sufficient numberand position to suspend the hosted device within the host module withoutsubstantial shock-transmitting contact with the host module other thanthrough the side rails and dampers.

At least some of the dampers are constructed of an elastic envelopecontaining a body of open cell material having orifices communicating atleast some of the cells with each other. A viscous liquid fills at leastsome of the cells, and another portion of the envelope contains acompressible gas within an air space.

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate preferred embodiments of the presentinvention, and together with the description, serve to explain theprinciples of the invention. In the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded isometric view taken from the upper left rear of aportable host module assembly employing mechanical energy-dissipativeelements, including optional features.

FIG. 2 is an isometric view taken from the front left side of theassembled module of FIG. 1.

FIG. 3 is an isometric view taken from the rear right side of theassembled module of FIG. 1.

FIG. 4 is a transverse cross-section taken at a vertical plane throughline 4-4 of FIG. 3, showing airflow through the module.

FIG. 5 is a longitudinal cross-section taken at a vertical plane throughline 5-5 of FIG. 3, showing airflow through the module.

FIG. 6 is a cross-section taken at a horizontal plane through line 6-6of FIG. 3.

FIG. 7 is an isometric view of a first portable hosted module in ejectedposition within a docking device and of a second portable hosted modulein inserted position.

FIG. 8 is an isometric view of a portable hosted module in insertedposition within a docking device.

FIG. 9 is a cross-sectional view taken at a vertical plane through line9-9 of FIG. 8. For clarity in showing airflow paths, mechanical energydissipative elements are omitted from this view.

FIG. 10 is an isometric view of a mechanical energy-dissipative elementin uncompressed condition.

FIG. 11 is an isometric view of a mechanical energy-dissipative elementin compressed condition, with a compressed open cell foam body inside anouter envelope shown in phantom.

FIG. 12 is a cross-sectional view of a mechanical energy-dissipativeelement taken along a vertical plane through line 12-12 of FIG. 10.

FIG. 13 is an enlarged, fragmentary view of one end of the mechanicalenergy-dissipative element of FIG. 12.

FIG. 14 is a view similar to FIG. 1 of a second embodiment of theinvention.

FIG. 15 is a view similar to FIG. 1 of a third embodiment of theinvention.

FIG. 16 is an assembly view of the third embodiment, showing a modifiedversion.

FIG. 17 is an assembly view of the second embodiment, showing a modifiedversion.

DETAILED DESCRIPTION

The invention is a ruggedized host module capable of protecting a hosteddevice from mechanical shock and vibration. A mechanicalenergy-dissipative element (MEDE) is effective in protecting the hosteddevice from many types of mechanical shock and vibration. Theenergy-dissipative element is well suited for use in a portable hostmodule for a hosted device. For example, a fixed disk drive or aremovable disk drive are typical hosted devices that may be packaged ina portable casing to create a removable drive module. The MEDE can beused between the hosted device and the casing to protect the hosteddevice. In this application, the MEDE enables an expanded range ofproducts to be offered in standard form factors, in which the hosteddevice must be compactly packaged to fit within dimensionally specifiedlimits.

Protection is possible from shock or vibration in many modes. Theenergy-dissipating element can protect by reducing external shock fromfree falls or drop by attenuating internal self-exciting vibrationforces, by attenuating acoustic energy emanating from the hosted device,or by increasing heat transfer from the hosted device. Particularly whenthe hosted device is a disk drive, it is a significant advantage that adamping structure operates effectively when placed between a disk driveand an encasing module to attenuate internal self-exciting vibrationforces emanating from a disk drive. Thus, terms such as shock andvibration refer to end results that may be initiated from any source orcause, including the hosted device, itself, or external events.

Hosted devices are not limited to disk drives. Numerous portableelectronics devices may beneficially serve as hosted devices. Commonexamples include personal digital assistants (PDAs), flash memorydrives, cameras, camcorders, and liquid crystal diode (LCD) panels.Further, hosted devices need not be portable. Fixed disk drives andother sensitive devices can benefit from protection even when mounted inlarge or stationary racks, cabinets, cases, and housings. A particularlypertinent example is a collection of similar fixed disk drives as oftenassembled in a RAID array. However, many types of equipment and devicescan benefit by damping inter-equipment effects, whether the devices areof the same type or different types.

Further, the hosted device need not be in operation or in a functionalindividual or group mounting. Protection also is necessary duringtransportation and handling, such as when a hosted device is in ashipping container. The MEDEs also can be effective when applied betweenhosted devices, individually or in modules, and between hosted devicesand a shipping container. Each hosted device can be protected both fromother hosted devices and from the boxing or crating as may be usedduring bulk transportation. Also, the MEDE can protect a hosted deviceduring other phases of handling, such as during installation.

The energy-dissipative element is a cost effective means for protectingany disk drive during shipment and installation. In an exemplaryembodiment described in greater detail hereinafter, the slim module isconfigured to provide maximum protection for a 3.5-inch form factor harddisk drive as well as to fit into a bay or docking device that occupiesa standard 5.25-inch form factor bay within a personal computer (PC).The standard latter bay is 14.6 cm (5.75 inches) wide. In addition, themodule provides vibration damping by viscous means. This permits use ofdrives with very high rotation speeds in system arrays, which typicallygenerate an increased level of vibration. The same module utilizing a2.5-inch form factor drive will withstand shock greater than 10,000 Gs.Viscous damping gives better protection than that obtained by using asingle or a combination of foam pads. Additionally, viscous propertiesof the material provide improved heat transfer and vibration andacoustic damping.

An exemplary embodiment is a module consisting of a 3.5-inch form factorhard disk drive and a set of viscous damping devices placed between thehard disk drive and a case made from shock resistant plastic. Thismodule protects the hard disk drive from shocks applied in all 6 axes (3of translation and 3 of rotation). The internal hard disk drive signaland power connections are applied using a flex PCA cable, flat cable andprinted circuit board assembly (PCBA) located at one end of the module.PCBA output can be connected to various kinds of external interfacecables or to a bay or docking device. Power to the stand-alone module isapplied via a mini-DIN connector mounted on to the internal PCBA.

The dimensions of a 3.5-inch form factor hard disk drive module are 35mm×115 mm×190 mm (1.38 in×4.53 in×7.54 in). This module is slightlylarger in size than a commercially available DataZone 2.5-inchruggedized module, but it can slide into the selected bay or dockingdevice.

The present invention provides a method and a system that dampensmechanical shock and vibration by means of a mechanical energydissipative element (MEDE). Each MEDE consists of numerousinterconnected cells containing a viscous, nonconductive liquid andoften a header of compressible gas. A matrix of such interconnectedcells may be provided in open cell elastic foam. A membrane, such as amembrane of foam material, defines each cell, and many of the cellshouse a pocket of viscous liquid. The vast majority of these cells haveat least one aperture through which the viscous liquid can enter or exitthe cell and flow from one cell to a juxtaposed cell. Each aperture issignificantly smaller in transverse dimension or cross section than thecells it interconnects. A relatively small aperture, as compared to thedimension of the cells, is desirable so that the aperture provides arestriction against liquid transit to or from the cell. The open cellfoam, viscous liquid, and compressible gas header are contained in asealed elastic housing that has shape memory so that after beingdeformed under compression or expansion, it tends to return to anoriginal or known prior configuration.

A preferred open cell foam is urethane foam supplied by E-A-R SpecialtyComposites of Indianapolis, Ind. Foams sold under the trademark Confor,and especially Confor CF-EG, are suitable. Densities and stiffnessdifferentiate several foams in this product line, which include CF-47Green, CF-45 Blue, CF-42 Pink, and CF-40 Yellow. The following tablesprovide representative data for each of the four listed foams andthereby provide guidance for selection of suitable alternate foams.TABLE 1 PROPERTIES OF CONFOR FOAMS (ENGLISH) CF-47 CF-45 CF-42 CF-40Green Blue Pink Yellow Nominal Density (pcf) 5.8 5.8 5.8 5.8 ASTM D3574Ball Rebound (%) ≦1.0 ≦1.0 ≦1.0 ≦1.0 ASTM D3574 Compression Set (%) 0.30.4 0.9 0.6 ASTM D3574 22 hr at 158 F. Compressed 25% Compressed 50% 0.60.6 1.0 2.4 Indentation Force Deflection 43 34 26 15 ASTM D3574 Test B1(modified) 25% Deflection: 72 F at 50% Relative Humidity TensileStrength (lbf/in) 25.2 22.3 18.1 14.6 ASTM D3574 20 in/min at 72 F. TearStrength (lbf/in) 5.5 4.6 3.4 1.6 ASTM D3574 20 in/min at 72 F.Elongation (%) 98 108 109 135 ASTM D3574 20 in/min at 72 F.

TABLE 2 PROPERTIES OF CONFOR FOAMS (METRIC) CF-47 CF-45 CF-42 CF-40Green Blue Pink Yellow Nominal Density (kg/m³) 93 93 93 93 ASTM D3574Ball Rebound (%) ≦1.0 ≦1.0 ≦1.0 ≦1.0 ASTM D3574 Compression Set (%) 0.30.4 0.9 0.6 ASTM D3574 22 hr at 70 C. Compressed 25% Compressed 50% 0.60.6 1.0 2.4 Indentation Force Deflection 43 34 26 15 ASTM D3574 Test B1(modified) 25% Deflection: 22 C at 50% Relative Humidity TensileStrength (kPa) 174 154 125 101 ASTM D3574 55 cm/min at 22 C. TearStrength (kN/m) 0.96 0.81 0.60 0.28 ASTM D3574 51 cm/min at 22 C.Elongation (%) 98 108 109 135 ASTM D3574 51 cm/min at 22 C.

CF-45 Blue and CF-47 Green are especially preferred foams for use inMEDEs for 3.5-inch form factor disk drives or similar other hosteddevices. CF-42 Pink has utility for use MEDEs with lighter weight hosteddevices such as 2.5-inch form factor disk drives. Confor foams are knownfor use as shock absorbing pads in disk drives and can dissipate up to97 percent of shock energy without recoiling and amplifying the effect.In hard disk drives, the foam alone can help protect againsthandling-related damage. Confor foam formulations, including CF-EGfoams, are engineered to compress and conform under sustained pressureand to slowly rebound when the shock is released. When the foams receivea direct impact, they behave like semi-rigid foams, resist collapse andabsorb the impact internally.

When mechanical forces, such as those caused by shock, vibration andacoustic waves, act to compress portions of an essentially open celledMEDE, the mechanical energy is dissipated by generation of forces thatsimultaneously drive pockets of viscous liquid through the apertures ofthe cells. After the period of compression of the MEDE by an externalforce has ended, the MEDE regains its original shape due to elasticnature of the housing and of the open cell material and due to capillaryaction. The expansion of the compressed cells and the elastic envelopewill continue until the viscous liquid returns to an establishedequilibrium state.

In many applications of the present invention, the MEDE comprises thefollowing essential elements: an elastic structure having a plurality ofopen cells; viscous, electrically nonconductive liquid distributedwithin the open cells; compressible gas, and an envelope enclosing theseelements.

The viscous liquid dissipates the energy of a mechanical shock due tohighly frictional shear forces within the liquid and between the liquidand cell walls as the liquid passes through narrower channels leadingbetween the individual open cells and between cells and the interior ofthe envelope. The liquid flow can be observed on a macroscopic level.The liquid and cells thereby provide a means to absorb and redirectundesirable mechanical energy that might otherwise damage or affect ahosted device in absence of such means.

The envelope is formed of an elastic material that: (a) helps thematerial within the MEDE to redistribute the viscous liquid and air intothe open cells after a mechanical shock has dissipated, and (b) permitsthe MEDE to regain its original shape. The elastic envelope material mayprovide additional shock absorption by acting like a spring deformed byan external mechanical force to store and subsequently release theenergy.

The fluids contained within the envelope are both a gas and a liquid.Air is a suitable gaseous fluid of very low viscosity. Preferred opencell foam is polyurethane foam. Such foams are known to have someinternal damping at the molecular level of the gas but none at amacroscopic scale as envisioned in the present invention. The presentinvention teaches the use of a highly viscous liquid flowing from onecell to another of the open cell foam or equivalent material and to andfrom the preferred embodiment with an elastic membrane enclosure of theMEDE. The envelope may be composed of latex tubing.

With reference to the drawings, FIG. 1 shows a portable module assembly20 in an exploded view. Main components include a hosted element 22which may be a disk drive, such as a 3.5-inch form factor hard diskdrive, or other shock sensitive component. A plurality of MEDEs 24surrounds the hosted element. A typical hosted device 22 has one or morepairs of opposite sidewalls or faces. As shown, a common configurationis block-like shape with six housing faces arranged in three pairs: atop and bottom, and two pairs of sides. The top and bottom are majorfaces, two relatively longer sides are intermediate faces, and tworelatively shorter sides are minor faces.

For protecting a hosted element configured similarly to a typical fixeddisk drive as shown in FIG. 1, MEDEs are configured in appropriatelengths for the shape of the hosted device and to accommodate the hosteddevice's cooling needs. A set of five MEDEs 24 protects the top of thehosted device, arranged around the top perimeter. A set of two MEDEs islocated on each longer sidewall of the hosted device, and two MEDEsprotect bottom of the hosted device. In the illustrated configuration,the topside MEDEs include a MEDE across the front edge of the top, whilethe bottom side MEDEs do not cover the front edge because an airflowinlet is located at that position.

The module 20 includes a case 26, FIGS. 2 and 3, which receives thehosted device. The MEDEs are mounted inside the case. The case includesa top cover unit 28 and a bottom cover unit or base 30 that mate tosurround the hosted device 22. The top cover 28 defines a top surface ofthe case, which is a major face. The bottom cover 30 defines a bottomsurface of the case, which is another major face. A perimeter skirtsurrounds the top and bottom surfaces, each forming part of thesidewalls. When the top cover and bottom cover are mated at a joiningline, their perimeter skirt walls define four sidewalls of the case,arranged as two opposite pairs of walls. The two pairs of sidewalls meetat four minor outside edges that may also be referred to as corneredges. Each end of a corner edge is a corner of the case. These cornersare likely to strike the ground first when the module is dropped, socorner bumpers specially protect them and secure the top and base.

The various MEDEs 24 are attached to the juxtaposed portions of the case26 or are attached to the contained, hosted device by any suitablefastening means, which conveniently may be double-sided tape or otheradhesive. MEDEs 24 may have an initial thickness of 3 mm (0.12 inch).When installed inside a closed case, these MEDEs may be compressed intoan available space of 0.2 mm (0.08 inch), thus resulting a preload offorty percent. In some applications, the case may have a greater spacingto the hosted device than the thickness of a single MEDE. FIG. 6 showsthat multiple MEDEs 24 may be assembled in layers, such as at the frontand rear ends of the hosted device, to fill available space. Where MEDEsare used in layers, they may be held together, such as by double-sidedtape, for purposes of assembly.

Corner bumpers 32 provide additional shock and vibration protection forthe hosted device and protect the case corners. In FIG. 1, four cornerbumpers 32 are attached respectively to the four minor outside corneredges of case 26. Each bumper 32 has sufficient height to extend beyondthe top and bottom walls of the case. Each bumper preferably is formedof an elastomer, and an elastomer material of thirty-five toseventy-five dm is preferred. The four minor corner edges of the casealso serve as a suitable location for fastening the top and base of thecase together with suitable fasteners such as screws. The bumpers 32 maycover and engage the four fastener locations. The bumpers can be moldedor transfer molded with rubber compounds using well-known processes. Thebumpers 32 are applied to the case 26 after cover 28 and the base 30 areassembled to form the completed case 26. Because bumpers 32 are locatedat the minor corners edges of module case 26, the bumpers are highlylikely to encounter first in contact with an impacting surface when themodule is dropped. The bumpers 32 reduce the transmitted shock to thecase 26 and in turn reduce the transmitted shock to the hosted device22. The bumpers 32 form a permanent part of module 20 and provide aprotective function during shipping, handling and installation. Thebumpers provide multi-axis shock protection.

Optional components of the module 20 are a circuit board 34 with a cableinterface 35, an internal flex cable 37 between the circuit board andthe hosted device, and an external cable 36 configured to engage thecable interface of the circuit board 34. The board 34 typicallytransmits input/output signals from the hosted device, and cable 36conveys signals to and from a computer. These optional componentstypically are used when the hosted device is a hard disk drive. Otheroptional elements may be selected and adapted for use as required forthe needs of different hosted devices.

The MEDEs 24 in the illustrated configuration support the mass of a 2.54cm (1-inch) high hard disk drive. The case size for a 3.5-inch formfactor hard disk drive is 35 mm×115 mm×190 mm (1.38 in×4.53 in×7.54 in).The case 26 beneficially can be made from impact resistant plastichaving properties similar to Cycoloy brand plastic, sold by GeneralElectric Plastics as item C2950. Cycoloy is an ABS plus polycarbonateplastic, unfilled, injection grade. It has 40% elongation at break, Izodimpact strength of 9.93 ft-lb/in, and is coated with a conductive filmon the inside for RFI shielding.

A desirable case configuration includes large slots 38 formed in cover28 and base 30. Additional, possibly smaller slots 40 may be formed inthe edges of base 30 or other locations and are best shown in FIGS. 4-6,where flow arrows suggest a path of cooling air through the housing 26.All of the slots contribute to conductive and convective heat transfer,which cools the hard disk drive or other hosted device. Another optionalcomponent, a fan 42, provides forced air-cooling.

A fully assembled portable module 20, FIGS. 2 and 3, houses a hosteddevice and MEDEs 24 within case 26. The bumpers 32 are shown in positionon the minor corner edges to protect all corners of module 20 and coverthe corner screw locations. Arrows in FIGS. 4-6 show a convectiveairflow pattern for cooling the hosted element. The compact structure ofthe MEDEs enables this pattern when arranged as shown in FIG. 1.Notably, other types of shock protection that employ foam pads may blockairflow and cause overheating difficulties.

The portable module 20 can be used in several different environments. Inthe embodiment of FIG. 5, the module 20 is suited for tabletop use.Airflow indicated by the arrows in FIG. 5 show a free convectionpattern. Both natural convection currents through the interior of themodule assembly and conduction through the thermally conductive viscousliquid in the MEDEs dissipate internal heat from the housing 26. Theoptional fan 42 enables forced convection. Airflow entering the front ofthe case 26 and exiting at the top and bottom of the case dissipatesinternal heat through forced convection flow.

In another operating environment, one or more modules 20 are installedin docking devices 44, such as in the array of two such docking devices44 shown in FIG. 7. The upper module shown in FIG. 7 is in partiallyejected configuration and shows a fan 46 located at the inner end of theupper docking device 44. The fan 46 is distinct from the optional fan 42in portable module 20, shown in FIG. 5. One or both fans can be used, asshown in FIG. 9. The lower module 20 is fully inserted into the lowerdocking device 44. FIG. 7 also shows that a plurality of modules 20 canbe mounted in an array that might be either part of a desktop computeror part of a rack system, discussed more fully below.

Still other operating environments include desktop computers and racksystems. In desktop computers, disk drives are placed in traditional5.25-inch form factor bays that are generally available for theirinstallation. Many mounting systems are known, including rails andscrew-in mountings. Mirroring boxes typically have two such spaces, andrack-mounted or tower RAID boxes have a plurality of such spaces. Adocking device 44 may occupy such a bay. In FIG. 8, the screw holes 45provide a means of mounting a docking device 44 in a standard bay. Theshock-resistant case 26 is suitably sized to slide into the dockingdevice 44 as shown in FIGS. 7 and 8. The case provides the additionaladvantage of making the module 20 portable. It may make use of matingconnectors, such as a Centronics or an equivalent male connector 55located on the board 34 inside the module 20 and a corresponding matingfemale connector 47 on the board of docking device 44. Generally, hotswap can be achieved with such a module 20 in a docking device 44.

One of the benefits of the MEDE dampers is that they attenuatecomplimentary vibrations between similar devices, such as a plurality offixed disk drives in a RAID array. A single mirroring function (RAID 1)can be implemented within a two bay box. A multiplicity of RAIDfunctions can be implemented in an eight bay, 3U wide tower orrack-mounted 3U high chassis. RAID 0, 1, 0+1, 3 and 5 configurations aretypically achieved in tower or rack-mount boxes. Generally, it takes acombination of three to eight modules 20 to achieve RAID architectureand the corresponding redundancy. The portable module 20 is ideallysuited for use in RAID configurations since it is portable and capableof withstanding high levels of vibration and shock.

FIGS. 10-12 show the structure of a MEDE 24. An external skin orenvelope 48 serves as a housing and contains other components of theMEDE. A highly resilient material such as latex rubber is the preferredmaterial for forming the envelope. An especially effective and efficientshape is longitudinally elongated, resulting in a latex tube being agood choice. At least one end of a tube conveniently is open forinserting additional components into the envelope. The embodiments ofFIGS. 10-12 show one end 50 that has been sealed after insertingcomponents into the tube. The second and opposite end 52 may beidentical to the first end 50. Alternatively, the second end 52 may beoriginally formed as a closed end, as shown in the drawings.

The envelope 48 contains a body 54 formed of elastic, resilient, opencell foam. FIG. 12 shows a matrix of interconnected cells in which theaperture between two cells tends to be of substantially smallercross-sectional area than either of the cells, themselves. Typicalaperture areas may be ten percent to twenty-five percent or more of thecross-sectional area of an adjacent cell. Thus, the apertures providerestriction to flow of viscous liquid. However, due to capillary actionand applied positive or negative pressure, the viscous liquid isflowable through the cells. The external geometry of the open cell foam54 determines the geometry of the envelope 48.

The envelope also contains viscous liquid 56, which may be dispersedthroughout the envelope and the open cells of the foam 54. The amount ofviscous liquid 56 within the envelope and foam inside it is controlledto fill the cells of the foam, fully or partially, so that a desiredshock response is obtained. As an example, a MEDE about four inches longcontains about two milliliters of 1,000 cs viscosity silicone fluid.Longer and shorter MEDEs, respectively, may contain proportionately moreor less silicone fluid. The following example illustrates how the MEDEsare structured and sized in one useful embodiment.

EXAMPLE

The portable module 20 houses a 3.5-inch disk drive weighing 680 gm (24ounces) and uses thirteen MEDEs. The materials and their respectivedimensions are as follows:

13 MEDEs per module (finished lengths approximate):

-   -   1. 4 MEDEs @ 13.34 cm (5.250 inch) finished size.    -   2. 1 MEDE @ 8.57 cm (3.375 inch) finished size.    -   3. 4 MEDEs @ 0.59 cm (1.5 inch) finished size.    -   4. 4 MEDEs @ 13.34 cm (5.25 inch) finished size.        Materials Needed:

1. Latex tubing, 0.254 mm (0.010 inch) wall thickness, 9.53 mm (0.375inch) I.D. (Kent Elastomer, Kent, Ohio, USA).

2. Open-celled polyurethane foam, Confor CF-47 Green, 9.53 mm (0.375inch) wide, 3.175 mm (0.125 in) to 6.35 mm (0.25 in) thick (E-A-RSpecialty Composites, Indianapolis, Ind., USA).

3. Viscous Liquid-polydimethylsiloxane (PDMS) silicone fluid, viscosity1,000 cs, (Aldrich Chemicals, Sigma-Aldrich Corp., St. Louis, Mo., USA).

4. Vulcanizing fluid, Rema Tip Top (North American, Inc., NorthvaleN.J., USA); or cyanoacrylate glue, Devcon Flex Super Glue No. 30340(Devcon Consumer Products, Riviera Beach, Fla., USA), or E6000 Glue(Eclectic Products, Carson City, Nev., USA).

Dimensions and quantities for 4 sizes: 1. Tubing: 15.24 cm (6 in) long  4 pcs. 2. Foam: 12.7 cm (5 in) × 4.76 to 6.35 mm   4 pcs.    (0.189 to0.25 in) 3. Silicone fluid: 1,000 cs   2 ml/MEDE 1. Tubing: 10.46 cm(4.12 in) long   1 pcs. 2. Foam: 7.92 cm (3.12 in) × 4.76 to 6.35 mm   1pcs.    (0.189 to 0.25 in) 3. Silicone fluid: 1,000 cs 1.65 ml/MEDE 1.Tubing: 50.8 mm (2.0 in) long   4 pcs. 2. Foam: 25.4 mm (1.0 in) × 4.76to 6.35 mm   4 pcs.    (0.189 to 0.25 in) 3. Silicone fluid: 1,000 cs 0.5 ml/MEDE 1. Tubing: 15.24 cm (6.0 in) long   4 pcs. 2. Foam: 12.7 cm(5 in) × 3.18 to 3.81 mm   4 pcs.    (0.125 to 0.15 in) 3. Siliconefluid: 1,000 cs 1.33 ml/MEDE

The compressible gas in the preferred embodiment is air. The viscosityof the silicone fluid was selected from a range of about 50 cs to 10,000cs. The viscous liquid is preferred to have a viscosity of less than10,000 cs and generally in a range from about 50 cs to 1,500 cs. Apreferred, effective range of viscosity for the uses described is about500 cs to 1,500 cs.

FIG. 12 shows a typical MEDE using an envelope 48 of elastic material.The end 50 of the envelope is sealed to prevent any leakage. The sealingcan be accomplished by any suitable means, which may include the use ofvulcanizing fluid, adhesive, or mechanical clamping. The drawingillustrates a representative mechanical clamp or band of shrinkabletubing 58 closing end 50. If adhesive is used, ethyl cyanoacrylate glueis preferred.

FIG. 13 is an enlarged view of a small region of this MEDE. In thisview, the open cell foam body 54 is enlarged to conceptually show cells60 that are filled to varying degrees with viscous liquid 58. Some cellsare partially filled with air 64 or other compressible gas such asnitrogen. The apertures between cells are relatively smaller than thetransverse dimension of the cells, themselves. The end of the envelopeprovides a void 66 that may contain air but also serves as a reservoirthat receives viscous liquid when the MEDE is compressed. This viscousliquid can return to the cells when the MEDE returns to uncompressedconfiguration.

A comparison of FIGS. 10 and 11 provide a conceptual illustration of aMEDE in compressed and uncompressed configurations. In the compressedconfiguration of FIG. 11, the viscous fluid has been displaced eitherinto cell areas that previously contained gas or into void areas 66.FIG. 10 shows a MEDE 24 before being subjected to shock loading. FIG. 11shows a similar MEDE under dynamic shock loading, i.e. when the velocityof an associated disk drive is near zero at the end of a shock event.Both FIGS. 10 and 11 show a single sealed end 50 of the envelope,although a similar sealed end may be used at both ends of a MEDE. Whenthe envelope is produced from a longer length tube, both ends aresealed. The length and cross-section of an MEDE may be different alongdifferent sides of a hosted device or hard disk drive. In order toproduce different sizes, different lengths and diameters of latex tubingmay be employed.

There are two mechanisms, both macroscopic, for dissipation and storageof mechanical energy. The flow of viscous liquid from a region of cellsunder compression to a region of cells under no direct load causescapillary flow through a multitude of orifices and also causes flow withrespect to cell walls. This leads to energy dissipation. Theaccompanying deformation of the cell walls of the foam and of theelastic envelope, which may be stretched, leads to storage of elasticenergy. This energy essentially restores the MEDE 24 to its unloadedcondition when the shock transient has subsided. The viscosity of theliquid and the volume of the cells are determined experimentally forreducing the shock transferred by the module case 26 to a hard diskdrive or other hosted device 22 to an acceptable level, such as may bespecified by the manufacturer.

The effectiveness of a MEDE was tested using a module 20 containing a3.5-inch form factor Hitachi Deskstar drive model #07N9685. The module20 was dropped from a height of 30.48 cm (1 foot) to 1.52 m (5 feet) sothat the broad side of the module impacted a linoleum-over-concreteslab. An accelerometer (model U350B23 made by PCB Pizotronics) wasplaced on the base of the drive thru a hole created in the case of themodule. LeCroy's digitizing Oscilloscope (model DDA125) was used torecord accelerometer output. The test showed that less than 200 G forcewas registered at five feet by the accelerometer and thus experienced bythe drive. A check subsequent to this five-foot drop verified drive readback of pre-recorded data without any errors, demonstrating thatread/write functionality remained intact. No known protective system incurrent commercial use has an ability to protect such a drive from fivefeet of free fall onto a linoleum surface.

The parameters considered in the design of the MEDEs for the preferredembodiment are the thickness of the latex envelope, type of foam, typeof fluid, its viscosity & quantity, and type of sealing procedure. Forthe preferred embodiment, Flex brand cyanoacrylate glue is used to sealthe ends. However, tubing made of heat-shrink material could be slippedover the ends and heat-shrunk to seal one or both ends, exemplifying atype of mechanical sealing.

The first failure mode of a disk drive is due to head-slap caused bylift off and subsequent drop of the magnetic transducer that issuspended on a spring lever above the surface of the recording media.Head-slap damages either the magnetic transducer or the recording media.Damage to the recording media generates debris that will later result inthe magnetic transducer “crashing” onto the recording media. The shockat which head-slap occurs defines the upper limit acceptable for theshock transmitted to a hosted hard disk drive 22. The arrangement anddesign of the MEDE 24 is critical in the axis in which the head willlift off the media because the transmitted shock has to be reduced toless than the upper limit acceptable to the hosted hard disk drive 22.The overall benefit of the MEDE 24 is to limit the decelerationexperienced by the hard disk drive 22 to less than 200 G. This is theusual shock limit specification for currently available hard diskdrives. Deceleration amplitudes below this limit do not result inhead-slap. The length and number of the MEDEs 24 used to protect fromshock in this direction are the controlling factors in design of thepreferred embodiment.

The second failure mode for shock to a disk drive involves thepositioner for the magnetic transducer moving from the “landing area”onto the recording area of the media. Special features of the “landingarea” prevent the head from sticking to the magnetic media when thedisks are not spinning. The disk drive contains a latch assembly toprevent motion of the positioner unless the disks are spinning. Withlarge rotational shock on the same axis as the axis of rotation for thepositioner, the latch will fail. Utilizing the viscosity of the viscousliquid, the mechanical energy dissipative elements are most effectiveagainst rotational shock because the transmitted shock is reduced to alower level than possible with prior known devices.

Form factor is an important consideration in producing a practicalproduct within an industry populated by large numbers of related,pre-distributed hardware units. An oddly sized product might be orphanedfor no other reason than its lack of conformity with the popular size ofsimilar products. Especially in the field of electronics and computerhardware, component sizes tend to diminish rather than increase.Achieving a successful, functional product within a standard form factorcan be a difficult challenge, especially in the field of ruggedizingelectronic components. Ruggedizing a component typically requires addingprotective elements around the component. Nevertheless, the size of aruggedized component must be similar to that of a non-ruggedizedcomponent so that it fits within available bays or spaces. Theruggedized component must be spatially compatible with related,pre-distributed hardware.

As described, the module 20 successfully contains a 3.5-inch form factorhosted device such as a hard disk drive 22. The size of case 26 is 35mm×115 mm×190 mm (1.38 in×4.53 in×7.54 in) and is sized to fit withinpre-distributed hardware having a bay of suitable size to accommodate5.25-inch form factor devices. Case 26 can hold both the hosted harddisk drive and the mechanical energy dissipative elements (MEDEs) 24. Itwould be desirable to further improve the ruggedized qualities of thehost module 20 without increasing the size of case 26.

One opportunity for improving the ruggedization of a module arises whena substitute for the hosted device is available in a smaller format. Oneexample of a smaller hosted element might be a hard disk drive of2.5-inch form factor, which can be substituted for a disk drive of3.5-inch form factor within the same case 26. However, a substitutioncan lead to additional technical problems, such as an increased tendencyfor the smaller hosted device to shift position on the case 26. Also,the smaller disk drive may lack sufficient contact surfaces to benefitfrom the originally designed structure and arrangement of the mechanicalenergy dissipative elements 24. Consequently, employing a 2.5-inch formfactor hosted device in case 26 can require a reconfiguration of theinternal components of the module.

With reference to FIG. 14, a second embodiment of the invention is ahost module assembly 70, similar to module assembly 20, but hosting asmaller hosted device such as a 2.5-inch form factor disk drive. In FIG.14, components that are the same or closely similar to those in FIGS.1-13 are assigned the previously used reference numbers.

The hosted device 72 is smaller in physical dimensions than the formerdisk drive 22. In order to prevent the smaller hosted disk drive frommoving excessively in the case 26, right and left longitudinal sideextensions or rails 74 are added to disk drive 72. The rails bring thehousing of drive 72 to approximately the width of a 3.5-inch form factordisk drive 22, effectively widening the housing of the hosted disk drive72.

Rails 74 are longitudinally elongated with four longitudinally extendingwalls or faces and two transverse end walls or faces. The rails 74 maybe thicker and longer than disk drive 72. The rails can be mounted tothe disk drive with the excess length at either end of the disk drive ordistributed between both ends. The rails are sized to preserve aclearance with top, bottom and sidewalls of the case, when case topportion 28 and the case base portion 30 are assembled around the hosteddevice. The rails 74 are attached to the hosted housing 72 by suitablefasteners such as screws 75 in order to secure the rails and housing asa unit. The longitudinal inner sidewall of each rail is juxtaposed to asidewall of the hosted housing 72. The remaining three longitudinal railwalls are a top wall, a bottom wall, and an outer sidewall.

Due to the comparative thinness of the smaller disk drive 72, thepreferred arrangement of mechanical energy dissipative elements ismodified. Specifically, at least one MEDE 76 is located against theouter sidewall of each rail, so that in the assembled case, the MEDE 76will be located between the rail and a sidewall of the case. At leastone other MEDE 78 is positioned against the top wall of each rail 74, sothat in the assembled case, the MEDE 78 will be located between the railand the top wall of the case. At least one further MEDE 80 is positionedagainst the bottom wall of each rail 74, so that in the assembled case,the MEDE 80 will be located between the rail and the bottom wall of thecase. The resulting structure encapsulates each rail on threelongitudinal faces by the use of at least three separate MEDEs 76, 78,80. The rails provide predictable, smooth contact surfaces for reactingwith the associated MEDES. In this way, the rails solve the technicalproblem that the surfaces of a hosted device are unpredictable inquality and suitability for interaction with MEDEs. Hosted devices mayhave been designed and manufactured without any anticipation that theyshould be compatible with MEDEs. Thus, a hosted device may have rough oruneven surface structures.

The hosted device or 2.5-inch form factor disk drive 72 of FIG. 14 is oflighter comparative weight or lower mass than a typical 3.5-inch formfactor disk drive. Typically, the former is about 113 gm (4 oz) whilethe latter is about 680 gm (24 oz). To best accommodate the needs of thelighter disk drive, the composition of mechanical energy dissipativeelements is modified. The body of open cell foam 54 may be chosen asConfor CF-42 Pink or an equivalent, which is more easily compressed andof lower tensile strength than CF-45 Blue or CF-47 Green or theirequivalents. The transverse dimensions of the foam bodies 54 may besquare, such as 9.53 by 9.53 mm (0.375 by 0.375 inches), which isapproximately double the thickness of MEDEs 24 described for use with3.5-inch form factor disk drives. The MEDEs 78 and 80, placed againstthe top and bottom surfaces of the rails of a 2.5-inch form factor diskdrive, may be five inches long, while the side edge MEDEs 76 are fourand one-half inches long.

The MEDEs may be adhered at least temporarily to the rails, such as bydouble-sided tape, in order to ensure that they maintain their desiredpositions through the assembly process. Alternatively, the MEDES 76, 78,80 or any of them may be adhered to the appropriate locations on theinside surface of case 26 for purposes of assembly. The MEDEs operate indirect contact with the top, bottom and outer sidewall surfaces of therails rather than with the walls of the hosted housing 72, itself. Thisarrangement produces a substantial open top space and open bottom spacebetween the hosted housing 72 and the respective case top cover 28 andcase base 30. At least one set of top and bottom case vents 38 is incommunication with this large open space adjacent to each major surfaceof the hosted housing 72.

The front and rear ends of hosted housing 72 enjoy a substantialclearance from the front and rear ends of the case. These clearances arepartially filled by a front block foam damper 82 and a rear block foamdamper 84. Either foam damper may be layered, split, or slotted topermit a cable such as cable 37 to pass through the damper in goodalignment with a connector on the hosted housing. Optionally, each blockof foam can be suitably notched and contoured to permit airflow throughthe previously described vents and to accommodate the interconnectionand operation of other components in the case, such as circuit board 34,an internal cable 37, as well as any desired optional additions, such asa fan. The block foam dampers 82, 84 also are contoured to contact thecase walls over broad areas to ensure efficient operation. The blockfoam dampers oppose the end walls of the rails 74 and space the railsfrom the end walls of the case. Because the rails are longer than thehosted device, the rails contact the foam blocks 82, 84 and establishfront and rear gaps between the foam blocks and the front and rear ofthe hosted device. This spacing allows ventilation currents through thecase between top and bottom of the hosted device.

The size of a 2.5-inch form factor disk drive is a 3.5-inch form factorcase allows substantial end space in the case. The foam dampers arecreated large enough to prevent a disk drive 72 from sliding into thefront or rear ends of the case even during a shock or impact event. Dueto their large size in the large front and rear areas, the foam dampersare effective substitutes for MEDEs at the ends of the disk drive 72.The resulting structure of damping elements places the MEDEs 76 at thesides, MEDEs 78 at the top, and MEDEs 80 at the bottom of the diskdrive, while foam dampers are found at both front and rear end.

The case further includes corner bumpers 32 that provide protective andsealing functions as previously described.

The rails 74 provide a surface area for face-to-face interaction withthe MEDES. In addition, the rails carry this surface area remotely fromthe disk drive and serve to isolate the disk drive from directlyreceiving shock. The rails provide smooth contact surfaces at their top,bottom and outer side faces, where MEDEs interact. These smooth facesprovide broad, uniform, substantially uninterrupted reaction surfacesthat interface with the MEDEs. Such uniform surfaces protect the MEDEsfrom damage by irregularities as might be encountered in the sidestructures of a hard drive or other hosted housing. These factorsimprove the ruggedized qualities of the module 70.

With reference to FIG. 17, the screws 75 that attach the rails to thehosted device may be suspended in rubber or elastomer grommets or otherresilient spacing dampers. Thus, screw hole bores through the rails 74may be counter bored from the outer sidewall, creating spacer receptionareas 86 each sized to receive a resilient spacer 87. The spacers 87 aresuitably sized as compared to the screws 76 to float each screw in oneof the spacers and isolate the screw from direct contact with a rail 74,when the screws are engaged through a rail and into the hosted device ordisk drive 72. The rails have a substantial thickness, such as thirteenmillimeters (one-half inch). Due to this thickness, more than onedamping spacer may be required to achieve a maximum damping result.Additional elastomer spacers or grommets 88 may be carried between therails 74 and the hosted device 72, in-line over the screws to serve asdampers between the rails and hosted device. According to otherarrangements, damping spacers or grommets may be placed between thescrew heads and the rails, or from either end within the screw passagesin the rails. The grommets provide additional protection against shockand vibration for the hosted device.

The advantages gained by using rails on a smaller hosted device, such asa 2.5-inch form factor disk drive, can be translated to provide improvedprotection for a larger hosted device. Thus, FIG. 15 shows a thirdembodiment in which a host module 90 carries a 3.5-inch form factorhosted device 92. As in the FIG. 14, components of FIG. 15 that are thesame or closely similar to those in FIGS. 1-14 are assigned thepreviously used corresponding reference number.

The hosted device 92 may be a hard disk drive that is similar in overallsize to a 3.5-inch form factor disk drive 22 of the first embodiment.However, a difference in disk drive 92 is that the top surface of thehosted housing 92 is irregular in contour. The top surface of thehousing 92 is contoured in various ways to accommodate interiorcomponents. Hard disk drives typically are designed and manufactured forgeneral-purpose usage and not specifically for use in a module assembly20, 70, or 90. Irregular contours of various descriptions may beincorporated into the housing for the disk drive according to themanufacturer's preference and need. Thus, the illustrated irregularcontour is an example and not a limitation.

Any surface having irregular contour can be a poor reaction surface forcarrying and cooperating with a MEDE. The MEDE may assume a partiallydistorted and compressed configuration over a contact area with theirregular features. When shock is received, the distorted area of theMEDE could fail prematurely. An irregular surface also is undesirablebecause it could cause the MEDE to shift its location over time. TheMEDE could shift away from its protective position on the raisedirregular contour, leaving the raised contour of the hosted housingunprotected or less protected against shock. Thus, a MEDE is bestcontained against and between surfaces of uniform contour and uniformspacing, without sharp structures that could puncture the MEDE.

As a protection to minimize the problem presented by an irregularsurface of disk drive 92, a leveling device such as a gasket 94 isapplied over the irregular top surface of the disk drive 92 in the viewof FIG. 15. The gasket is of a thickness, pattern, and contour toproduce a uniform top surface on disk drive 92. The central cutout ofgasket 94 is readily seen to be a close match for the irregular raisedpattern on the original top wall of the disk drive 92. Rubber or similarresilient material is a suitable choice for constructing the gasket 94.When gasket 94 is applied to the top wall of disk drive 92, it producesa smooth mounting surface for receiving a MEDE and for the MEDE to pushagainst during a shock event.

Leveling the contact surface of a hosted device is a partial solution tothe problem of irregularities. A further and related problem is that aleveled surface may have areas of different widths having differingqualities. Thus, a device for creating a uniform surface can be appliedalong selected portions of a hosted device, with or without theassociated use of a leveling gasket. As further shown in FIG. 15, asurface layer 95 of flexible and tough sheet material covers the gasket94 and a portion of the top surface of a hosted 3.5-inch form factordisk drive 92. A suitable material for layer 95 is Mylar brand polyesterfilm, a trademark and product of E.l. du Pont de Nemours and Company ofWilmington, Del., United States of America and worldwide. This top layercovers the perimeter of the top surface of disk drive 92, coveringportions of the gasket 94, where used, and portions of the original topsurface. A central portion of the surface layer 95 is cut-away or opento vent heat from the disk drive. The uniform surface layer 95 isespecially desirable to cover screw heads that otherwise may be exposedthrough gasket 94 and to establish a uniformly wide surface atappropriate areas to receive and react with a MEDE.

Side rails 96, such as right and left side rails, are attached to diskdrive 92 as additional means to isolate the disk drive from shock and toprovide a smooth mounting and reaction surface for a MEDE. In thisembodiment, the disk drive is of a form factor already matching the formfactor of the case 26 and has little spare room on lateral sides. Thus,the rails 96 are formed of shaped sheet metal and add only minimally tothe lateral dimensions of the housing of disk drive 92. Each rail 96 isconfigured as an L-shaped angle bracket in which two planar plates ofsheet material meet along a perpendicular junction of major faces. Afirst planar plate of the rails lies parallel to a sidewall of the diskdrive 92 and partially overlaps it, serving as a mounting plate forattaching the rail to the disk drive 92. The second planar plate lies atan acute angle to the first, typically perpendicular to the first andoffset from a major face of the disk drive as a free wall. The free walllies parallel to a major surface such as the top or bottom face of thedisk drive 92 and at least partially overlaps it. Thus, each rail addsto the lateral dimension of the disk drive 92 only by approximately thethickness of the sheet material. Screws 98 attach the rails 96 to thedisk drive 92 at standard mounting positions provided by the disk drivemanufacturer, such as through the side plates of the rails. The screws98 have modified heads designed to be smooth and without sharp edges.

A significant benefit of rails 96 is that the second planar plate orfree wall is offset from a juxtaposed major face of the disk drive andoverlaps an area of the disk drive that typically carries an exposedprinted circuit board or other irregular surface. The components of aprinted circuit board typically are sharp and irregular, such that theycould damage a MEDE by contact. The L-shaped rail formed of sheet metalcan provide a strong, pressure resistant freestanding wall over anexposed irregularity, especially over an irregularity that is unsuitedfor coverage by a gasket 94. The free wall of the rail forms a suitablereaction surface over an exposed printed circuit board to allow a MEDEto function properly. The free wall of the rail provides both a suitablylarge area and smooth surface suitable to serve as the reaction wall fora MEDE. Thus, the use of L-shaped rails or another such device forproviding a free wall allows the use of MEDEs against a broader range ofhosted devices, including those with exposed printed circuit boards orother irregular surfaces, without substantially increasing thedimensions of the hosted device.

Mechanical energy-dissipative elements provide shock protection to themajor faces of the disk drive 92. Two MEDEs 78 are applied to the topface of disk drive 92 in proximity to respective opposite side edges ofthe top surface, against gasket 94 or Mylar surface covering 95. Theseright and left top MEDEs can be adhered to the gasket or Mylar covering,at least temporarily for assembly, by double-side tape. An additionaltwo MEDEs 80 are applied to the bottom of disk drive 92 against therespective bottom plates of the rails 96. These right and left bottomMEDEs are adhered to the rails, at least temporarily, by a double-sidedtape. With a longitudinal dimension of about 4.5 inches, MEDEs 78 and 80are almost as long as the front-to-rear dimension of the disk drive 92.These MEDEs are approximately centered along the side dimension of thedisk drive 92 in order to provide protection throughout the length ofthe drive.

Although the rails 96 contribute little to the width of the disk drive92, due to the constraints of meeting 3.5-inch form factor dimensions,their presence possibly could compromise the function of a MEDE placedon the side plate of the rail. In the embodiment of FIG. 15, a perimeterband 100 replaces such side MEDEs. This band is selected for good shockabsorption qualities. A suitable band is formed of a plastic foam sheetmaterial. The band may be about 13 mm (0.5 inch) in height and the sheetmay have a thickness of about 7.9 mm (0.3125 inch). A preferred foam forthis purpose is open cell urethane foam such as CF-47 Green, supplied byE-A-R Specialty Composites of Indianapolis, Ind., sold under trademarkConfor, as mentioned, above. Double-sided tape can adhere the foam stripto the disk drive and rails.

The disk drive 92, with attached rails, MEDEs, and foam perimeter strip,is assembled into the case by uniting housing top 28 to base 30. Suchfeatures as a fan 42, electronics board 34, cable 37, and false wall 102are included as needed or desired. Corner screws 104 secure the casehalves together. Corner bumpers 32 cover the screws and provideadditional shock protection at the corner edges.

In a variation of the arrangements shown in FIG. 15, FIG. 16 shows ahosted device 92 that is suited to receive side rails 96. The side railscan be the L-shaped rails 96, although other shapes also may besuitable. Sidewall screws 98 attach the rails to the sidewalls of thecase. Side MEDEs 76 are positioned against the sidewalls of the railsand against the front and rear sides of the device 92.

With or without the rails 96, the hosted device 92 includes at least twopairs of two opposite sidewall faces, which are the front and rear facesand the two opposite side faces. These sidewall faces are positioned ina substantially continuous perimeter around the hosted device. At leastfour mechanical energy dissipative elements 76 surround the hosteddevice 92 at the perimeter established by the sidewalls.

Optionally, where lateral space is sufficient, the use of thin sheetmetal rails 96 may permit the use of dampers 99, which are positioned injuxtaposition to the rails and screws to provide additional protectionagainst transmission of shock and vibration. Dampers 99 may be of rubberor elastomer material. Rubber grommets are a suitable example.Preferably, the grommets are mounted in the screw passages of the rails,such that the ends of the grommets extend from both ends of the screwpassage. The screws 99 fasten the grommets to the hosted device, and thegrommets engage the rails, without any direct contact between the screwsand rails.

Other possible arrangements include placement of the grommets betweenthe rails and the hosted device, or placement of the grommets betweenthe screw heads and the rails. As previously described, thicker rails74, FIG. 14, may require the use of multiple grommets, such as separategrommets at the entrance face and exit face of a screw passage.

As described and illustrated, a hosted device 72, 92 is carried in ahost module assembly 26 and protected from deleterious mechanical shocksand vibrations. Side rails 74, 96 are attached to opposite edges of thehosted device 72, 92 to isolate the hosted device from direct receptionof shock. A plurality of elastic dampers 76, 78, 80 are applied betweenthe side rails 74, 96 and the host module 20 in sufficient number andposition to suspend the hosted device within the host module withoutsubstantial shock-transmitting contact with the host module other thanthrough the side rails and dampers.

This method and apparatus can be applied to a wide variety of hosteddevices and hosted housings. It is especially useful when applied todisk drives where space and size can be at a premium in order to complywith a known or popular form factor. At least some of the dampers 24 canbe of a space-efficient and size-efficient variety in which an elasticenvelope 48 contains a body 54 of open cell material having orificescommunicating at least some of the cells 60 with each other, a viscousand electrically nonconductive liquid 56 filling at least some of thecells, and an air space 66 containing compressible gas 64. The methodenables the use of other types of dampers to supplement the MEDEs 24.These may include foam plastic blocks 82, 84, foam plastic bands 100,and grommets or other resilient spacers 87, 88, 99.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be regarded as falling within the scope of the invention as definedby the claims that follow.

1. An energy dissipative element for use in protecting a hosted devicefrom deleterious effects of mechanical shocks and vibrations, the energydissipative element comprising: a closed envelope formed of an elastic,resilient wall and enclosing an internal volume; a porous body ofelastic material contained within the internal volume of said closedenvelope, wherein said body defines a network of cells interconnectedthrough cell orifices suitably configured for passing viscous liquidbetween cells; and a viscous liquid of viscosity less than 10,000centistokes contained within said envelope and filling at least aportion of said network of interconnected cells, wherein undercompression or expansion of the porous body, said viscous liquid flowsthrough said cell orifices and thereby dissipates energy resulting froman external force applied against said elastic wall; and a compressiblegas occupying a portion of the internal volume of the envelope.
 2. Anenergy dissipative element, as claimed in claim 1, wherein: said closedenvelope is composed of a material having shape memory such that afterbeing compressed or expanded the closed envelope tends to return to aprior shape.
 3. The energy dissipative element of claim 1, wherein saidclosed envelope includes at least one end having adhered surfaces,wherein: a cyanoacrylate glue adheres shut said adhered surfaces of saidenvelope.
 4. An energy dissipative element, as claimed in claim 1,wherein: said viscous liquid is a silicone fluid.
 5. An energydissipative element, as claimed in claim 1 wherein: said elasticmaterial is of tensile strength between about fourteen and twenty-fivelbf/in.
 6. An energy dissipative element, as claimed in claim 1 wherein:said viscous liquid is of a viscosity between about 500 and 1,500centistokes.
 7. A host module assembly for protecting a hosted devicefrom shock and vibration, including a case that is suitably configuredto receive a hosted device therein and a hosted device located withinthe case, wherein said hosted device includes a housing having at leasttwo opposite sidewalls, a top wall and a bottom wall; and the hostmodule includes a mechanical energy dissipative element formed of anelastic envelope containing a body of open cell material having orificescommunicating at least some of the cells with each other, a viscousliquid filling at least some of the cells, and an air space containing acompressible gas, wherein the host module assembly further comprises: atleast one rail carried on at least one of said sidewalls, wherein saidrail is configured to have at least one exposed wall of suitable sizeand surface characteristic to serve as a reaction surface forinteraction with said mechanical energy dissipative element; and whereinthe mechanical energy dissipative element is positioned against saidreaction surface of the rail.
 8. The host module assembly of claim 7,wherein: each of said rails has at least two exposed faces of suitablesize and surface characteristic to serve as a reaction surface forinteraction with said mechanical energy dissipative element; said caseis suitably sized to receive at least one of said mechanical energydissipative elements between each of said two exposed faces of saidrails and the case; and at least two of said mechanical energydissipative elements are located between each of the rails and the case,with at least one mechanical energy dissipative element located betweeneach of said two exposed faces of each rail and the case.
 9. The hostmodule assembly of claim 7, wherein: each of said rails has at leastthree exposed faces of suitable size and surface characteristic to serveas a reaction surface for interaction with said mechanical energydissipative element; said case is suitably sized to receive at least oneof said mechanical energy dissipative elements between each of saidthree exposed faces of said rails and the case; and at least three ofsaid mechanical energy dissipative elements are located between each ofthe rails and the case, with at least one mechanical energy dissipativeelement located between each of said three exposed faces of each railand the case.
 10. The host module assembly of claim 9, wherein: saidthree exposed faces of each rail are longitudinally elongated anddisposed approximately parallel to said top, bottom and side faces ofsaid hosted device; and said rails are longitudinally elongated by agreater dimension than the length of said hosted device.
 11. The hostmodule assembly of claim 7, wherein said case is configured with atleast one external corner, further comprising: a bumper formed ofelastomer material and attached over said at least one corner.
 12. Thehost module assembly of claim 11, wherein the elastomer material of saidbumper is of 35 dm to 75 dm.
 13. The host module assembly of claim 11,wherein: said case is composed of a base unit and a cover unit that meetat a joining line to form said case; and said bumper is attached over aportion of both said base unit and said cover unit, securing togetherthe base unit and cover unit.
 14. The host module assembly of claim 7,wherein: said rail is composed of a mounting wall and a free wall angledacutely to said mounting wall, wherein said free wall is positioned tooverlap a portion of said top wall or bottom wall of said hosted device;and said free wall is of suitable size and surface characteristic toserve as a reaction surface for interaction with said mechanical energydissipative element.
 15. The host module assembly of claim 7, wherein:said housing of said hosted device further includes two opposite endwalls; said rail includes a rail end portion extending longitudinallybeyond at least one of said hosted device end walls; and furthercomprising: a damper located between said case and said extending railend portion, whereby a ventilation gap is maintained between said hosteddevice and said damper.
 16. The host module assembly of claim 7, whereinsaid hosted device includes a housing having at least one face ofirregular surface contour, further comprising: a leveling means formating with said face of irregular surface contour to produce a face ofregular surface contour; and wherein said at least one mechanical energydissipative element is located between said face of regular surfacecontour and the case.
 17. The host module assembly of claim 7, whereinsaid hosted device includes a housing having at least one non-uniformface, further comprising: a means for establishing a uniform surface,mated to said non-uniform face to produce a uniform face; wherein saidmeans for establishing a uniform surface covers a peripheral portion ofsaid non-uniform face over a selected width; and wherein said at leastone mechanical energy dissipative element is located between saiduniform face and the case.
 18. The host module assembly of claim 7,wherein: said hosted device is a disk drive; and said case is of acommon form factor selected from a 3.5-inch, 3.0-inch, 2.5-inch, or1-inch form factor; whereby said mechanical energy dissipative elementprovides a ruggedized disk drive system of a common form factor.
 19. Thehost module assembly of claim 7, wherein: said hosted device is a diskdrive; and said case is a shipping container, whereby the disk drive isprotected from shock and vibration during transportation and handling.20. The host module assembly of claim 7, wherein: said hosted device isa portable electronics device.
 21. The host module assembly of claim 7,wherein: said hosted device is selected from the group consisting ofpersonal digital assistants (PDAs), cameras, camcorders, and liquidcrystal diode panels.
 22. The host module assembly of claim 7, whereinsaid hosted device includes a hosted housing having at least four wallsarranged as a first pair of two opposite walls and a second pair or twoopposite walls, wherein the second pair of opposite walls connects thefirst pair of opposite walls, wherein: said at least one rail comprisesa pair of rails respectively attached to said hosted housing at saidfirst pair of opposite walls, each of said pair of rails furthercomprising at least two planar rail walls, wherein a first of saidplanar rail walls overlaps one wall of said first pair of oppositehousing walls and is attached thereto, and a second of the planar railwalls overlaps one wall of said second pair of opposite housing walls;and at least one of said mechanical energy dissipative elements islocated between each rail of said pair of rails and said case and isjuxtaposed to said second planar rail wall.
 23. The host module assemblyof claim 22, further comprising: an energy absorbing foam plasticperimeter band located between said hosted housing and said case,wherein said perimeter band overlaps said first planar rail walls. 24.The host module assembly of claim 22, further comprising: an elastomericspacer interposed between at least one of said rails and said hostedhousing.
 25. A method of protecting a hosted device carried in a hostmodule assembly from deleterious mechanical shocks and vibrations,comprising: isolating the hosted device from direct reception of shockby attaching side rails to opposite edges of said hosted device;applying a plurality of elastic dampers between said side rails and saidhost module in sufficient number and position to suspend said hosteddevice within the host module without substantial shock-transmittingcontact with the host module other than through said side rails anddampers.
 26. The method according to claim 25, wherein at least some ofsaid dampers comprise: an elastic envelope containing a body of opencell material having orifices communicating at least some of the cellswith each other; a viscous liquid filling at least some of the cells;and an air space containing a compressible gas.